7. O____ vegetables are those that are grown without c______ that can be harmful to human beings or the _________(环境).

6. The car doesn’t f__ well; I think you’d better have it repaired.

5. If you are s_________, you had better go to bed.

4. Don’t give me meat any more. I am on a d_________.

3. Doctors advise us not to eat fruit which is not r_________.

2. Young people always have more e_________ than the old.

1. Do you know that a worker ant has two _________(胃)?

31. Only in this way __ find the way of solving the difficult problem.

A. you can　　　B. would you 　 C. can you　　　　　D. you will

30. The old farmer cut up the old tree for his winter ______.

A. supplement　 　　B. product　　 　 C. fuel　　　　　　 　　D. choice

29. I ______ her, but I never could.

A. ought to help　　 　　 　B. must help　　　 　

C. ought to have helped　　D. must have helped